(1) Field of the Invention
The present invention relates to a coffee machine for producing and dispensing coffee beverages, in particular an espresso machine, having a housing in which are disposed at least one brewing device, a container for coffee beans, a grinding device connected to this container, a feed hopper for feeding the ground coffee beans into a brewing chamber of the brewing device, a stripper for the leached ground coffee, at least one hot water boiler, comprising a fresh water supply line and a hot water line coming out into a brewing chamber of the brewing device, a coffee dispensing nozzle and a control unit by means of which the dispensing of coffee is controllable.
(2) Description of Related Art
Coffee machines of this kind are known in many variations. Thus shown, for example, in GB-A-956 109 is a coffee machine of this kind. Coffee machines for restaurant businesses, coffee machines for industrial firms as well as coffee machines for households can be equipped according to this system.
In order to be able to obtain as good a quality of coffee as possible dispensed from the coffee machine, the temperature of the water in the brewing chamber which blanches the ground coffee should be at as constant a temperature as possible (for instance 95° C.). However it is a fact that the hot water located in the hot water boiler has a higher temperature since this water cools down on the way between the hot water boiler and the brewing chamber. This cooling down is not the same with each dispensing of coffee, however; in particular it depends on whether it is a first dispensing of coffee during which the lines and the valve through which the hot water will run as well as the brewing chamber are in a cold state, or whether these areas are warmed up owing to the passage of the hot water for previously dispensed coffee. Depending upon the situation, the brewing water can have too low or too high a temperature, which can affect the quality of the coffee dispensed.
An important factor which likewise affects the quality of the coffee to be dispensed is the pressure, with which the water is pressed through the brewing chamber. However this pressure can be kept at a constant value relatively well, using known means.